Depression is a mood disorder that causes persistent feelings of sadness and loss of interest, impacting both physical and mental health. It has often been ignored as a minor issue not requiring medical help, but depression is a real illness with symptoms and should be treated. There are several types of depression, including postnatal depression affecting many new mothers, seasonal affective disorder which is more common in winter months, and bipolar disorder with major mood swings. Causes of depression include stressful life events, other illnesses, and low self-esteem. Treatment options are exercise, antidepressant medication, and therapy which can help manage depression.